<template>
  <div class="s-canvas">
    <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
  </div>
</template>

<script>
    export default {
        name: "verificationCode",
      props: {
        identifyCode: {
          type: String,
          default: "1234"
        },
        fontSizeMin: {
          type: Number,
          default: 35
        },
        fontSizeMax: {
          type: Number,
          default: 35
        },
        backgroundColorMin: {
          type: Number,
          default: 180
        },
        backgroundColorMax: {
          type: Number,
          default: 240
        },
        colorMin: {
          type: Number,
          default: 50
        },
        colorMax: {
          type: Number,
          default: 160
        },
        lineColorMin: {
          type: Number,
          default: 100
        },
        lineColorMax: {
          type: Number,
          default: 200
        },
        dotColorMin: {
          type: Number,
          default: 0
        },
        dotColorMax: {
          type: Number,
          default: 255
        },
        contentWidth: {
          type: Number,
          default: 120
        },
        contentHeight: {
          type: Number,
          default: 40
        }
      },
      methods:{
        // 生成一个随机数
        randomNum(min, max) {
          return Math.floor(Math.random() * (max - min) + min);
        },
        // 生成一个随机的颜色
        randomColor(min, max) {
          let r = this.randomNum(min, max);
          let g = this.randomNum(min, max);
          let b = this.randomNum(min, max);
          return "rgb(" + r + "," + g + "," + b + ")";
        },
        transparent() {
          return "rgb(255,255,255)";
        },
        drawPic() {
          let canvas = document.getElementById("s-canvas");
          let ctx = canvas.getContext("2d");
          ctx.textBaseline = "bottom";
          // 绘制背景
          // ctx.fillStyle = this.randomColor(
          //   this.backgroundColorMin,
          //   this.backgroundColorMax
          // );
          ctx.fillStyle = this.transparent();
          ctx.fillRect(0, 0, this.contentWidth, this.contentHeight);
          // 绘制文字
          for (let i = 0; i < this.identifyCode.length; i++) {
            this.drawText(ctx, this.identifyCode[i], i);
          }
          // this.drawLine(ctx)
          // this.drawDot(ctx)
        },
        drawText(ctx, txt, i) {
          ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax);
          ctx.font =
            this.randomNum(this.fontSizeMin, this.fontSizeMax) + "px SimHei";
          let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1));
          let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5);
          var deg = this.randomNum(-10, 10);
          // 修改坐标原点和旋转角度
          ctx.translate(x, y);
          ctx.rotate((deg * Math.PI) / 180);
          ctx.fillText(txt, 0, 0);
          // 恢复坐标原点和旋转角度
          ctx.rotate((-deg * Math.PI) / 180);
          ctx.translate(-x, -y);
        },
        drawLine(ctx) {
          // 绘制干扰线
          for (let i = 0; i < 8; i++) {
            ctx.strokeStyle = this.randomColor(
              this.lineColorMin,
              this.lineColorMax
            );
            ctx.beginPath();
            ctx.moveTo(
              this.randomNum(0, this.contentWidth),
              this.randomNum(0, this.contentHeight)
            );
            ctx.lineTo(
              this.randomNum(0, this.contentWidth),
              this.randomNum(0, this.contentHeight)
            );
            ctx.stroke();
          }
        },
        drawDot(ctx) {
          // 绘制干扰点
          for (let i = 0; i < 100; i++) {
            ctx.fillStyle = this.randomColor(0, 255);
            ctx.beginPath();
            ctx.arc(
              this.randomNum(0, this.contentWidth),
              this.randomNum(0, this.contentHeight),
              1,
              0,
              2 * Math.PI
            );
            ctx.fill();
          }
        }
      },
      watch: {
        identifyCode() {
          this.drawPic();
        }
      },
      mounted() {
        this.drawPic();
      }

    }
</script>

<style scoped>

</style>
